Types of signals?

It's Network Rail infrastructure north of Queen's Park and it's equipped with Network Rail signalling - generally three aspect colour lights - operated from Wembley Suburban Signalling Centre, an IECC-type installation.

Here's a fun fact, though. Signal WS8 is the junction signal giving access to Queen's Park platform 1 and the up DC lines towards Kilburn High Road and Euston (main aspect only) or the Bakerloo line (position 4 junction indicator). Signal WS8 will only clear with the diverging route (onto the Bakerloo) if there is an LU headcode in the TD berth and the train correctly operates the negative shoe detector in rear of the signal.

What's more, if a train with an LU headcode is signalled to Kilburn High Road to reverse, the up starter at Kilburn High Road (WS2) will be placed and maintained at danger until the wrong road starter WS7 has been cleared and the platform track has become unoccupied. This is because the fourth rail runs out just outside Kilburn High Road.

Any more? The down station starter at Harrow & Wealdstone's down platform, WS55, giving access to the down DC lines towards Watford Junction (main aspect), or the turnback siding for LU trains (position light shunt signal) had a terrible reputation as one of the most frequently SPADed signals in the country. That may have improved in recent years.

www.railsigns.uk/photos/p_overrun1/p_overrun1.html#pic_harrow

You're right, WS24 is some way from the platform. I'm not sure, but I believe it's quite hard to see from Harlesden station - possibly invisible.